Would rhodos or hydrangeas survive in containers (like large barrels), or do they have to be planted in the ground to survive? If so, how large of a container would be needed? And are there different kinds of these plants that would be better suited to growing in a container? Even though I live in the suburbs of Vancouver, we still get more snow than the rest of the Lower Mainland in the winter -- would this pose more of a hazard to the plants if they are in containers? Thanks.